8 papers · 1 filter
On the maximal subgroups of almost simple and primitive perfect groups
Patricia Medina Capilla, Luca Sabatini
We prove that, if is a finite almost simple group and is a maximal subgroup of , then the th term of the derived series of is perfect. The same is true if is…
Cayley graphs of quasirandom groups
Luca Sabatini
A finite group is -quasirandom if all its nontrivial irreducible complex representations have degree at least . Building on recent work of Golsefi…
Expanding groups with large diameter
Sean Eberhard, Luca Sabatini
We study how the spectral gap and diameter of Cayley graphs depend strongly on the choice of generating set. We answer a question of Pyber and Szabó (2013) by exhibiting a sequenc…
Groups that produce expander graphs
Luca Sabatini
We survey the known group properties that a sequence of finite groups or group actions needs to satisfy to admit subsets of bounded cardinality producing expander Cayley or Schreie…
Quasirandom and quasisimple groups
Marco Barbieri, Luca Sabatini
Fix . We say that a finite group is -quasirandom if every nontrivial irreducible complex representation of has degree at least $|G|^\varepsilo…
On stabilizers in finite permutation groups
Luca Sabatini
Let be a permutation group on the finite set . We prove various results about partitions of whose stabilizers have good properties. In particular, in every solvable pe…